Load transfer device for concrete pavements



Aug. 2%, 1952 JACQBSQN' 2,608,141

LOAD TRANSFER DEVICE FOR CONCRETE PAVEMENTS Filed April 26, 1947 2SHEETS-SHEET l 1952 J. H. JACOBSON 2,603,141

LOAD TRANSFER DEVICE FOR CONCRETE PAVEMENTS Filed April 26, 1947 2SHEETSSHEET 2 Patented Aug. 2.6, 1952 V 2,60s, 14'i LOADATRANSFER DEVICEoaooNoitE'rE PAVEMENTS James Hi Jacobson; Chi'cagoJll;AppIicationApriI-QG, 1947 -Serial-No;:7 4el,242

8 Claims.

This invention relates 'to' improvements in Portland cement concretepavement construction and relates particularly to: improvements indevices for transferring loads across a joint separatingadjacent-pavement panels. e

In, modern concrete pavement construction it is, the practice toprovideat regularly spaced intervals meansfor permitting contraction orexpension. of the-pavement slabs, and the presence of such separatorsqorspacer. members-between the adjacent slabs requires the useof means fortransmitting loads on .one. pavement panel into an adjacentpavementpanel across such. a joint, to :the. end that such loads may.beproperly dis.- tributed across such. a joint :and that .the 'pave mentslabs will not be misaligned vertically:

In the past it has beenthepractice to employ round-dowels made of hotrolled steel, thedowels extending across the joint and beingibondedinonepavement panel andfree of bond-inthe adjacent pavementpanel, acapbeing provided at the endofthe unbondedportion of the dowels; toprovide for expansion of the concreteslab; More recent practice has beento encircle such dowelswi-th a sleeve or other means to'diminish thebearingstresses-on the concrete-caused by the load transferred by-thedowels; particularly at-the vertical-facesof the concrete adjacent thejoint.-

An object-of the present invention is to provide for concrete pavementconstruction a load transfer device which' is made oitwo co-operatingsimilar and symmetrical complementary members or portions; each ofwhichis positioned in the concrete mass on each side of a joint 'or spacermember, the two complementary mem-' bers or portions interlocking witheach other and being in mutual bearing, each" of the comple'-'mentary-members or portions preferably havingan arm-which is struckbackinto the concrete mass to anchor each portion of the load transferdevice firmly into thec'oncrete.

' A yet-further object is to provide a load transfer device whichisunusually-rigid and whichcomprises a pair of co-operating-..symmetrical complementary members or portions, each mem- Another. objectis to providea load transfer deyicewhich is formed of two symmetrical.com.-. plem'entary members or portions which write 2 manufactured byforging, punching; or'cas' Other objects ofthe'invention, will be apfifro'm' 'a 'study'of the de'scription'hereinaftei"taken together with the.drawingsin which: I Figure" 1 is "a side elevation viewo'f afloadtransfer device according to the present inven? tionj'showing' thedevice positioned in a concrete slab'which is shown in secti'c'injFigure 2' is a section taken. along theIIin sQ- -Z ofFigure 1:"

Figure s is a sec"tion"taken "along 'the' lines 3 -3 ofFigure l';' e iFigure 4 is an end view of thefload transfer 'dej vice shown in Figure1; i Figure'5 is an isometric View showing in detail how theco-ope'rating Symmetric l'commementary members "or 'portions "of theload transfer device of Figure 1 are fitted together; and I I Figure 6isan elevation view of anotheriorm of theinvention. Referring now'toFigures' l to'5, th'eload t'ra i fer device according to the present.invention is indicated generallypy' the ordinal ID, and is shownin"'conj'unction with a spacermmterlz whichsep'aratestwo adjacent coniete' paiasm and Hit The spacer member 12 maybeprot ectd alon'g' 'its'upper edge 'by means, of ta 'U-channell8 andalo'n'g its'lowei edee'by'a'similar "'u 5riaifiii The load transfer device "l O'a'lsb comprises "tw'similar co-operatingsymmetrical complementary member'sor portions; eachmember or portion ink. clu'di'ng' a channel" portion 22 which d-o' ra swith a tenon" 24' 'of the" opposite, likeiand sym metrical'mein'b'ei' or"portion, Each channel pertion"22."is provided with hearingsurfacesg26'and 28" upon which the tenon 24is affordedmutual slidingbearing support with the channel portion 22.- The channel portion iscomposed of a web and upper "and; lower flangesand the channel thereofis open throughout its entire; length to permit'lat'eral assemblymovement of the comple: menta'ry members or portions. As shownin Fig:ure 1,. the 'tenons- 24 pass through 'openingsflll,

inthe spacer member I 2 Each co-ope rating symmetricalportion of theload transfer device in isprovided withva'n-arm' 32 which extends fromeach channel 22-and lies' in the exposed iaces of the concrete; panelscrslabs'l l and I-E, a nd each is con'tinuouswith- PO tions 34 s'trucl:back into the concrete pane, j and It. The portions 3}} may be flared,seeiFige ures 4, and 5, as at 35' to provide more areaz'fori bond-withits 'contig iouspavement panel. -Each charmer 221s provided with adowtwamy'airected extension 38 which lies in the faces of the concretepanels I4 and I6 when poured and adjacent the spacer member I2.

It will be apparent that the device thus far described can be anchoredfirmly into a concrete pavement and can be employed to transfer a loadon one concrete panel, as for example panel I4 into the adjacent panelI6. The device thus far described will also operate to, permit;expansion and contraction of the panels I4 and I6 since the tenons 24have a sliding bearing fit with the channel 22. In order to permitmovement of the tenons 24 with respect to the channel 22 a portion ofthe channel 22 not having the tenons 24 slidable therein is providedwith a plug of easily deformable material 40, see Figure 3 also, whichmay be made of sponge rubber, fibrous material made from bagasse, orother suitable similar material. I

Means are provided for holding the device thus far described together asa unit with the spacer member I2, to the end that the entire assemblymaybe placed on the subgrade prior to the concreting operation. There isprovided a basket indicated generally by the ordinal 42 which comprisesa pair of stringers 44 resting on the subgrade, as shown, and extendinglongitudinally of the spacer member I2. The stringers 44 are connectedby a stirrup 46 in the general form of an inverted W, the stirrup 46having a pair of vertical legs 48 which springably engage the downwardlydirected extensions 38 with the spacer member I2 and the channel member20 held therebetween. Secured to each of the stringers 44 and on eachside of the spacer member I2 is a saddle 50 having a pair of centrallegs 52 which springably engage the channel 22 and the material 40.

Referring now to Figure 6, another embodiment of the invention is shown.As shown in Figure 6 the load transfer device, according to thisembodiment of the invention, is indicated generally by the ordinal I Iand is shown as being used in conjunction with the spacer member I I2which may be made of thin bituminous impregnated material, or of a steelplate, such being generally employed where joints for contraction areneeded. The spacer member H2 separates adjoining pavement panels I I4and I I6. The upper edge of the spacer member II2 may be protected bya-cap channel H8, and the lower edge of the member II2 may also beprotected by a channel member I20. The load transfer device IIOcomprises a pair of similar co-operating symmetrical portions, eachportion having a channel I22 into which extends a tenon I24 of theopposite symmetrical portion, the tenon I24 being in close slidingbearing fit on surfaces I26 and I28 of the channel member I22. Thetenons I24 are adapted to pass through a rectangular opening I30 spacedin the spacer member II2. Each channel portion I22 has a downwardlydirected extension I38 which lies in the faces of the concrete panels H4and H6 when poured and on each side of the spacer member I I2. Thetenons I24 do not extend in the channels I22 for the full lengththereof, and the portions of the channel I22 not occupied by the tenonsI24 are filled with readily deformable material I40 in order to providefor unimpeded movement of the tenons I24 with respect to the channelsI22 upon contraction or expansion of the concrete panels I I4 and I I6,and to prevent the entrance of concrete to the channels I22 during thepaving operation.

- The device described with reference to Figure 6 may be held togetheras a unit with the spacer member II2 by means of a basket assemblyindicated generally by the ordinal I42 and which, as with reference toFigure 4, comprises stringers I44 and stirrups I46 having upstandingportions I48 which engage the extension I30 with the spacer member II2of the channel I20 therebetween. The ends of the channel I22 are held insaddles I50 in a manner exactlylike that shown in Figure 4.

The load transfer devices described above consist essentially of twosimilar cc-operating symmetrical portions which may be readily formed byone or more processes or methods. For example, each portion may be cast,and the channels milled to provide a bearing surface for the tenon whichis milled to a size to obtain a sliding bearing fit with the channel. Inorder to obtain the necessary ductility for the co-operating symmetricalportions, and in order to take the impact stress caused by loads uponthe concrete panels, the parts are malleableized. The load transferdevice disclosed in Figures 1 to 6 inclusive may alternatively beforged, the'present date forging processes permitting the holding oftolerances which enable the tenons to have a close sliding bearing fitwith the channel of the opposing symmetrical portion. The device mayalso be made by a punching operation which would give channelsheld tosuch close dimensions that they would readily provide a sliding bearingfit with a tenon also made in the punching operation.

While the invention has been described in terms of a preferredembodiment thereon, its scope is not limited in terms of the embodimentshown nor otherwise by the terms here appended.

I claim:

1. A load transfer device for use in concrete slab constructionincluding two cooperating symmetrical complementary members eachcomprising a channel portion and a tenon consisting of an extension ofthe web of the channel portion and, the tenon of each channel portionbeing received within and fitting the channel of the other channelportion and supported by the same to maintain said members in mutualsupporting relation, each of said channel portions being provided at itsinner end with an extension of the upper flange of the channel memberextending upwardly and outwardly therefrom and arranged to extend intoan adjacent concrete slab when poured.

2. A load transfer device for use in concrete slab constructionincluding two cooperating symmetrical complementary members eachcomprising a channel portion and a tenon consisting of an extension ofthe Web of the channel portion and the tenon of each channel portionbeing received within and fitting the channel of the other channelportion and supported by the same to maintain said members in mutualsupporting relation, each of said channel portions being provided at itsinner end with an arm consisting of an extension of the upper flange ofthe channel member and extending upwardly therefrom and having its upperportion bent back and arranged to extend into an adjacent concrete slabwhen poured.

3. A load transfer device for use in concrete slab constructionincluding two cooperating symmetrical complementary members eachcomprising a channel portion and a tenon consisting of an extension ofthe web of the channel portion and the tenon of each channel portionbeing received within and fitting the channel of the other channelportion and supported by the same to maintain said members in mutualsupporting relation, each channel portion having at its inner end adownwardly directed extension of the adjacent flange of said channelportion arranged to lie in the joint face of a contiguous concrete slabwhen poured.

4. A load transfer device for use in concrete slab constructionincluding two cooperating symmetrical complementary members eachcomprising a channel portion having horizontal upper and lower flangesand a vertical web and a tenon consisting of an extension of the web ofthe channel portion and the tenon of each channel portion being receivedwithin and fltting between and engaging the flanges of the other channelportion and supported by the same to maintain said members in mutualsupporting relation, each channel portion having. its upper flangeextended upwardly and forming an arm bent back and arranged to extendinto an adjacent concrete slab when poured, and each channel portionhaving its lower flange extended downwardly and forming a downwardlydirected extension arranged to lie in the face of said concrete slabwhen poured.

5. A joint for concrete pavement construction comprising a spacermember, load transfer devices spaced longitudinally of the spacer memberand adapted to transfer loads from a concrete panel on one side of thespacer member to a concrete panel on the other side of the spacermember, each load transfer device comprising two cooperating symmetricalcomplementary members, each member being provided with a channel portionconsisting of a web and upper and lower flanges, an a tenon, the tenonof each channel portion being an extension of the web thereof andfitting between and engaged by the flanges of the other channel portionand each channel portion having a downwardly directed extension arrangedto lie in the joint face of a contiguous slab when poured and adjacentthe spacer member, and means for holding the spacer member and the loadtransfer devices together as a unit assembly comprising a basket havingportions engaging the said channel portions and portions engaging saiddownwardly directed extensions with the spacer member therebetween.

6. A joint for concrete pavement construction comprising a spacermember, load transfer devices spaced longitudinally of the spacer memberand adapted to transfer loads from a concrete panel on one side of thespacer member to a concrete panel on the other side of the spacermember, each load transfer device comprising two cooperating symmetricalcomplementary members, each member being provided with a channel portionconsisting of aweb and upper and lower flanges, and a tenon, the tenonof each channel portion being an extension of the web thereof andfitting between and engaged by the flanges of the other channel portionand each channel portion having a downwardly directed extension arrangedto lie in the joint face of a contiguous slab when poured and adjacentthe spacer member, and means for holding the spacer member and the loadtransfer devices together as a unit assembly comprising a basket havingsaddles springably engaging said channels and including stirrupsspringably engaging said extensions with the spacer therebetween.

'7. A joint for concrete pavement construction comprising a spacermember, load transfer devices spaced longitudinally of the spacer memberand adapted to transfer loads from a concrete panel on one side of thespacer member to a concrete panel on the other side of the spacermember, each load transfer device comprising two cooperating symmetricalcomplementary members, each member being provided with a channel portionconsisting of a web and upper and lower flanges, and a tenon, the tenonof each channel portion being an extension of the web thereof andfitting between and engaged by the flanges of the other channel portionand each channel portion having a downwardly directed extension arrangedto lie in the joint face of a contiguous slab when poured and adjacentthe spacer member, plugs arranged within the channel portions at theouter ends thereof adjacent the outer ends of the tenons of the members,and means for holding the spacer member and the load transfer devicestogether as aunit assembly comprising a basket including a pair ofstringers extending one each lengthwise of the spacer member, stirrupsconnecting said stringers and springably engaging said extensions withthe spacer member between, and saddles connected to said stringers andspringably engaging said plugs and the channel portions near the endsthereof and retaining the plugs in said channel portions.

8. A load transfer device for use in concrete construction comprisingtwo cooperating symmetrical complementary members, each of said membersbeing provided with a channel portion and a tenon, each channel portionhaving flanges which form a bearing surface engaging and supporting thecooperating tenon of the other member, each channel portion having itsupper flange extended upwardly at its inner end and forming an armextending upwardly and arranged to lie in the joint face of a concreteslab when poured, said arm having a portion bent back with respect tothe joint face of a concrete slab when poured, and each channel portionhaving its lower flange extended downwardly and forming a downwardlydirected extension arranged to lie in the joint face of a concrete slab.

JAMES H. JACOBSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Yeoman Aug. 15, 1944

